View topic - Slow I/O ? QNX 6.5 SDP with Intel 3420 chipset (Dell R310)

Slow I/O ? QNX 6.5 SDP with Intel 3420 chipset (Dell R310)

Discussion about the QNX6 OS.

Slow I/O ? QNX 6.5 SDP with Intel 3420 chipset (Dell R310)

Postby mohsh86 » Thu Oct 27, 2011 10:04 am

ok, so lastly we are planning for QNX 6.5 upgrade, i am planning to Get dell R310 with simple SATA Controllers (no RAID what so ever)

the Dell R310 i have has the fake raid PERC S300, i've disconnected it from board, and disabled it in bios, and put the SATA mode to ATA (only 2 options available ATA & RAID), and connected the harddrive directly to SATA board

*QNX while booting detected as EIDE device*

QNX 6.5 installed fine, but here is the issue: (Slow I/O ?)

1. during installation copying from CD to hardware was going like bursts of data, copying 5% and will hold like for 10 secs
2. the same thing i noticed while copying or extracting Archive from External USB drive to the HDD
3. the same issue with extracting an archive that exists on the harddrive it self

is it an Intel 3420 chipset issue ?
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Re: Slow I/O ? QNX 6.5 SDP with Intel 3420 chipset (Dell R3

Postby Tim » Thu Oct 27, 2011 4:44 pm


It sounds like the devb-eide driver is not using DMA mode. If you have Photon installed (or run hogs if you only have terminal mode) and copy/extract a large file do you see CPU use jump to 100% with devb-eide using the CPU. If that happens it means the driver is not using DMA mode and all disk I/O will be VERY slow.

If this is the case it may just be that the chipset isn't reporting to the driver in a way it understands. There are options to devb-eide to force DMA mode (also called udma). There is also a nobios option to tell the driver not to use BIOS transfer settings (which may be whats confusing the driver) One of these will probably fix your problem.

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